1. Field of the Invention
This invention concerns a cooker particularly but not necessarily exclusively for use by troops on deployment.
2. Description of the Related Art
Deployed troops need, of course, to be provided with hot food whenever possible, but sources of cooking fuel are limited. Nevertheless many previous cookers have been proposed for use by troops on deployment. Typically such cookers have a diesel-fired burner (diesel fuel being widely available) arranged to heat a container of water wherein food is cooked, or prepared food such as pouch meals or ration packs are heated. The cookers may be located in temporary deployable accommodation (TDA).
Some popular foods such as chips, doughnuts and fried chicken need to be cooked in fat rather than water, and this introduces a risk that the fat will be carbonised, and as a result food cooked therein will be tainted. (For the avoidance of doubt it should be noted that the term “fat” as used herein includes cooking oils). This risk is most notable (a) when solid cooking fat is first heated, especially where there are voids in the fat, and (b) when liquid cooking fat has been previously used and contains residual food particles. Further, for safety (especially in TDA) it is important to keep the temperature of the cooking fat below its flash point of around 320° C.
It is difficult to meet these requirements in a portable cooker such as may be used by troops on deployment. Most such cookers are designed for heating water. An example of this is the tray ration heating system described in International Patent Application WO 2005/018391, which has a water reservoir heated from a firebox and is notable for recording a temperature of 1945° F. (=1063° C.) immediately below the reservoir adjacent the firebox and a temperature as high as 962° F. (=517° C.) at the end of the reservoir away from the firebox—that is, temperatures greatly above the flash point of cooking fat. An example of a portable cooker designed for frying is described in European Patent Application EP 0560552, and this shows a container of cooking oil having a gas-fired combustion chamber within the container and in direct contact with the oil, from which it is evident that the oil close to the combustion chamber will necessarily be much hotter than the rest of the oil and therefore at risk of carbonising. Those skilled in the art will note also that the arrangement of EP 0560552 is difficult to clean, having the combustion chamber within the cooking container, and this increases the likelihood of residual food particles in the oil.
It is an object of the present invention to enable fat to be used in a portable cooker without a substantial risk of the fat being overheated.